The phenomenon of compressor stall has become an important limiting factor in the operation of gas turbine engines as their performance characteristics have improved. In modern gas turbine engines, upon acceleration or under high altitude and lower speed flight conditions, unstable flow may develop in the compressor which can lead to a stall with a resultant increase in turbine temperature and mechanical vibration along with a simultaneous reduction in cooling air supplied to the turbine wheel. These conditions describe "compressor stall" and can lead to turbine failure if the compressor stall is not recognized and corrective action not taken. Turbine failure during engine operation can lead to severe engine and aircraft damage.
To avoid such damage, control systems have been proposed to detect the onset of compressor stall and either signal the aircraft pilot or automatically compensate to bring the engine out of the stall condition. It has been found that functions of certain engine operating parameters can provide an indication of stalled engine conditions. Systems have been designed which monitor these parameters to detect compressor stall. Several previous attempts to develop stall warning indicators have used either engine operating pressures, pressure ratios, speed or temperatures as input parameters.